Cognitive Science, Institute of Behavioural Sciences, University of Helsinki, P.O. Box 9, 00014 Helsinki, Finland.
Neurosci Lett. 2012 May 10;516(1):141-5. doi: 10.1016/j.neulet.2012.03.076. Epub 2012 Apr 2.
Brain oscillatory responses of 4-35 Hz EEG frequencies elicited during performance of a visual n-back task with complex visual stimuli were assessed in 20 adult volunteers. Spectral power changes were assessed separately for target and non-target stimuli in four different memory load conditions (0, 1, 2, and 3-back). The presentation of both target and non-target stimuli elicited long-lasting ~4-8 Hz power increases, which were more prominent at the beginning of stimulus onset during presentation of target stimuli, as compared to non-target stimuli, in the 0-back memory load condition. ~8-25 Hz power decreases appeared at stimulus onset. These power decreases were more prominent during the presentation of target stimuli, as compared to non-target stimuli, and their duration increased as a function of memory load between the 0-, 1-, and 2-back, but not the 3-back, memory load conditions. The current results provide further evidence in support of the notion of a complex interplay between both ~4-8 Hz power increases and ~8-25 Hz power decreases during cognitive memory task performance.
在 20 名成年志愿者中评估了执行具有复杂视觉刺激的视觉 n 回任务期间 4-35 Hz EEG 频率的脑振荡反应。在四种不同的记忆负荷条件（0、1、2 和 3 回）下，分别评估了目标和非目标刺激的光谱功率变化。与非目标刺激相比，在 0 回记忆负荷条件下，呈现目标和非目标刺激都会引起持续时间较长的4-8 Hz 功率增加，而在目标刺激呈现期间，这种增加在刺激开始时更为明显。在刺激开始时出现8-25 Hz 的功率下降。与非目标刺激相比，这些功率下降在目标刺激呈现期间更为明显，并且它们的持续时间随着记忆负荷的增加而增加，从 0-1-2 回，但不是 3 回的记忆负荷条件。目前的结果进一步支持了在认知记忆任务执行过程中，4-8 Hz 功率增加和8-25 Hz 功率下降之间存在复杂相互作用的观点。
